SNES Mini RGB mod gone wrong

I know I messed up. I fully admit that.
So I did the RGB mod using the THS7314 amp following the instructions from retrorgb.com. I finished and everything worked great! The RGB image was a little too bright so I continued the mod by adding 1.2k Ohm resistors. I made sure to shrink tube each resistor like the tutorial says. I plug in the SNES and the image was yellow with a bunch of noise. I ended up removing the entire mod resetting the SNES Mini back to factory default. It still has a noisy yellow picture even through composite. I tested the av cable on a fat SNES and it worked fine. Did I fry or short out the PPU? My only thought at this point it to lift the RGB pins off the PPU and hand wire them to the built in S-RGB amp. Perhaps the flood of yellow is coming from the Red and Green shorted somewhere I cannot see? What else would be generating the noise and yellow screen?
I am really mad at myself for screwing this one up. I probably should start by changing the caps.

 

Please leave the caps alone for now. Focus on the area you worked on:
Are any traces shorted now? Use you multimeter to check for continuity.
Measure the resistance from the CPUN RGB out pins to the video encoder input.

 

Maybe some pictures could help...
Have you falsely solder the resistors to TC + instead of TC -?

 

Thanks for the response. I actually did use a multimeter and checked for continuity but I forgot to mention it. The RGB pins appear to have correct separate continuity. When I get a chance tonight, I'll check the resistance from the CPUN RGB out pins to the video encoder input.

 

Okay. Also check if the outputs are connected to their pads (since you undid the THS mod, right?) and they don't come in contact with anything else

 

I am positive I connect the resistors to the negative TC. When I get a chance tonight, I'll post pictures.

 

I'll will double check everything again. I will post pictures tonight.

 

So I realized that the CPUN blue out was severed from the board at the excess pin. The blue access pin is slightly damaged overall. I soldered the connection back in place and was able to get continuity on both side of the pcb again. Nothing changed, still a yellow tinted image.

Clearly the color output is still missing blue. I then soldered a wire from CPUN blue directly to the S-RGB blue in. The image output got much brighter and the colors changed. I wonder if the blue excess pin is damaged in a way that it's being grounded? The strange thing is that when I had the CPUN blue excess pin soldered back to the board, I was able to get continuity to ground but not consistently. Maybe I'm crazy but this clearly needs a lot more investigating. I wish I could find a diagram of the pcb traces and see when the blue out goes before hitting the S-RGB.
http://imgur.com/a/2GYgN

 

Connecting the blue channel output of the S-CPUN to the S-RGB directly overdrives the input. Try to figure out, where something on the board went wrong.
Between the S-CPUN and the S-RGB you have R8 going to GND (150ohms) and C8 (a 0.082uF ceramic capacitor) in series.

for me it looks like that you have shortened blue and green.

 

Thank you for the info. This is exactly what I was looking for. I will run tests over the weekend. This whole thing has been extremely flustrating because I was very careful when I did the mod. I'm getting to the point where I want to remove the video completely off the board and hand wire it with proper caps and resistors.

 

Keep us posted. I had this same issue happen years ago and I never solved it.

 

Still, sometimes we make errors. The skill is to take a step back, look at one's action, and then derive a way to fix them.
I've messed up a fair share of soldering jobs but in each single case, I could repair my damage. Just don't give up because you don't understand a problem yet!
Ask around. People will remember issues they had in the past, and they'll be able to help you fix yours

 

Did you install THS7314 amp or do the 3 wire mod? I wonder if heating up the RGB excess pins a few times fried the CPUN causing a short directly in the chip. I'm almost on the verge of cutting all the RGB traces and wiring my own although there is no going back at that point.

 

It's possible you damaged the vias (through-holes) for the B signal when soldering the 1.2k resistors. They could be tricky, they are sensitive. I would test from one side of the board to the other, or test from the CPUN B output to the R8. You should have a short. Might be easy to check the vias if you had like a 10x loop or some type of magnifying lens. If you want to bypass the via, you would have to solder a wire from the B output to R8 side that is not tied to GND, and solder a 1.2k resistor across R8 (in parallel).

 

Is there a guide somewhere that shows how to install the RGB mod on the SNES? I just did the mod on my n64 and was wondering if the SNES was similar?

 

http://retrorgb.com/snesminisrgb.html

 

Thanks for the post. Do you know if its possible to do this on a regular fat snes? I couldn't see any link on their page immediately.

 

Are you wanting to use a THS7314 amp, or are you just wanting RGB in general? If the latter, stock regular SNESs output RGB by default, no modification needed.

 

Oh really? Could I use the same cable with my RGB n64? It's got the sync over Luma. Don't know if that matters.

 

Yup, it'll work.